Percutaneous leadless pacemaker implantation in a patient with bilateral venous thoracic outlet syndrome

We describe the case of a 71-year-old patient with highgrade atrioventricular block and sick sinus syndrome who was referred for implantation of a dual-chamber pacing system. Conventional pacemaker (PM) therapy requires a subcutaneous pacing generator and transvenous leads, commonly implanted via the subclavian vein. In patients in whom this transvenous route is not available, epicardial electrodes may be used as an alternative. The transvenous PM procedure failed because the right ventricle (RV) could not be reached by the subclavian venous route due to an obstruction. Contrast venography showed filling defects with extensive collateral veins formation confirming the stenosis in the left and right subclavian veins, suggesting the diagnosis of bilateral venous thoracic outlet syndrome (TOS) (Figure 1(a) and (b)). Therefore, the procedure was aborted. TOS is an uncommon vascular phenomenon, with an overall reported incidence of approximately 0.3%– 0.7%.1,2 TOS can be categorized as vascular, including arterial or venous, neurogenic from brachial plexus compression, and a mixed form of neurogenic and vascular TOS.1,2 Venous TOS accounts for only 3% of TOS cases.3 Most of the deep vein thromboses in the upper extremity are secondary to catheters or indwelling devices. Review of a thoracic computed tomography (CT)-scan performed several years previously to rule out pulmonary embolism showed the same vascular abnormalities, suggesting a long-standing and stable condition. The patient had a very uncommon presentation of venous TOS since there were no clues in the patient’s history as to the cause of the obstructions. No trauma, no excessive exercise, and no previous intravascular procedures were reported. Recently, a novel endovascular approach of pacing therapy has become available: a leadless pacemaker (LP) that is transfemorally inserted into the right ventricular cavity. Since our patient had a pacing indication, the use of an LP was considered as the most suitable alternative therapy. The LP (Micra: Medtronic Inc., Minneapolis, MN, USA) was inserted by a catheter delivery system through the right femoral vein with the use of a 23-French introducer.4 The catheter was inserted into the RV, and the LP was fixated to the myocardium in the apex with the nitinol tines located at the distal end of the device. The implantation was completed without complications and with adequate electrical parameters (right ventricular sensing of 9.7 mV, impedance of 740 ohm, and a pacing threshold of 0.38 V at 0.24 ms) (Figure 1(c)). The patient was discharged 1 day post implant. The patient developed no complications during a follow-up of 1 year and resumed all normal activity. Our findings suggest that LP implantation is an effective solution in patients with a pacing indication affected by bilateral venous TOS. This situation might also apply to hemodialysis patients, who commonly need central venous catheters and where the presence of vein thrombosis or PM wires can be problematic. Although not addressed in current guidelines, this percutaneous approach may be considered as an alternative strategy for conventional transvenous dual-chamber pacing in selected cases to avoid implanting an epicardial system.